I would recommend (a) explaining this to him-- how it makes you feel, the anxiety, your concerns for the future-- because it's a big issue, and while he probably "knows," he probably doesn't know how hard it is for you. That conversation could be revealing.

And (b) making a plan for yourself in how to handle it when he gets irritable. This kind of follows from the above conversation, because if your plan is to leave him alone until he cools down, it's kinder to tell him that in advance rather than leave him wondering why you're not there. But YOU are important. If you intend to stick it through with this guy, focus on what's best for you to do when this happens.

Personally-- and obviously situations and interests differ-- I could not handle this situation and would be gone so fast, whether he had a reason for his anger or not. I was raised in an explosive household and I'm familiar with that anxiety and pain and worry-- it's really horrible. I ended up spending most of my time afraid, closed-off, and defensive-- it's hard to have a relationship with someone when you're always on eggshells around them. Therapy and medications can help him with this, but it's been a consistent problem, and it's a way of thinking/reacting to the world-- it will probably be there for some time, and it may never entirely go away.